Tuesday, March 02, 2010

Pardon me for the pun, but a chain of people have been linked with Shimano chain failures.

Consider this an update to the my first post where a reader alerted me to his concern that large batches of Shimano's Ultegra chains have been failing recently. The said person worked for a cycling magazine so he was probably witnessing this first hand with his access.

In that post (click here if you haven't read it), readers and me agreed that a possible suspect may be related to heat treatment that may be causing the links to become brittle. However, at this point, there's insufficient test data to back that thought.

As to what the heat treatment protocol it is that chain links undergo is not within my knowledge. If there are industry insiders reading this who want to help provide insight, please feel free to join in with a comment.

Within days of writing the post, I obtained news of more instances of failure.

Case 1 :This Shimano 6700 chain, used by Roger failed after just 2500km of use. He wrote to me that he had kept it well lubricated and had never cross-chained excessively (and never with force), yet it broke in the exact same manner as in the images that were shown here. According to him, he had never broken a chain before and would usually swap them out only after 10,000km or so. Apparently, he had them sent back to Wiggle and when Shimano was contacted about it, they didn't recognize the problem.

Case 2 : A blogger with Team BBC in Baltimore, Maryland posted a tweet showing his Ultegra chain that broke in a matter of just 7 days. According to him, it was installed as per the instructions yet he was caught by surprise when he found cracked side plates while lubing the chain today. He also remarked on Twitter that another racer from the same area fell and lost some skin after his Ultegra chain broke while he attempted a "track stand". The following pictures were posted on his blog.

Case 3 : I received a quick note from Jonathan Judd yesterday telling me his story. He did not have any pictures for me. I quote him :

"My Ultegra chain broke 25km into a ride on Saturday. That was the first ride the bike had ever done - brand new. I had climed for around 300 meters in altitude gain without any problems. It was after the descent when I dropped onto the small chain ring (under virtually no pressure) that the chain broke. Initially I thought it had over shot the small chain ring but then I saw it hanging down into the road. Luckily I had a chain tool and spare connecting pin. But 25km is shockingly poor!"

Shimano has not recognized the problem nor have they issued an official statement in spite of multiple failures. It is suggested that they do a root cause study and issue a recall of product from the market if itisdefective.

20 comments:

Wiggle offered to send me a free replacement chain. They've spoken to Shimano and they still don't see the problem. I politely declined Wiggle's generous gesture stating that I will not use Shimano chains again until they acknowledge that there is an issue with chains having such a short lifespan.

Jobst Brandt had the following to say when I showed him these pictures :

"I've written about faulty heat treatment of chains over the years and recently. I had SRAM and Regina chains that cracked and broke apart around rivets. Ordinary steel stretches orbends but it doesn't crack in a visually brittle mode. This is a lot like hard anodizing rims and having them crack apart... as they did massively when the ill advised use of the method was introduced by rim manufacturers. You shouldn't wonder why I say the bicycle industry is too poor to hire good engineers. There's no one in charge in the engineering department."

This observation may not be related to the mentioned failures, but all these chains (and chainrings) are appallingly dirty (for having been ridden so little). I'm going to assume wet to slushy conditions. If slush, there may be salt from the road in with all that muck.

I think the Toyota comment might have some relevance. It seems to me that the Japanese business culture is to never admit a failure or problem until you have no choice. Toyota had problems in the past with engines where the oil would sludge up and as I remember they denied it until they were forced to admit it.

It's a manufacturing problem, caused by over hardness (brittleness) of the plates and/or possibly a minutely undersized hole which increased the interferance fit beyond tolerance and over stressed the plate at the hole.

Chain manufacturing is a straightforward process, but entails working with very tight dimensional, material, and heat treating tolerances. The trend to narrower and lighter chains narrows the working tolerances considerably, leaving almost zero margin for error. This kind of problem is likely to become more common in the future, so good QC and good vigilance by consumers is important.

Those have to be some of the worst maintained chains I've seen. Even if the failures weren't caused by lack of maintenance - regularly cleaning and lubing your chain might give you a chance to see a crack before riding on it again!

Also - who the heck uses Ultegra chains? And why? The cost savings over the Dura Ace is insignificant.

I have just detected several stress failures of the same nature on a new and well maintained chain, I was totally amazed when I found them, one I could accept, a chain full is rubbish. Perhaps Shimano should be advertising these chains as single use only no more than 600Km!

Four chains...all 6700 broken. I just finished pulling out of one of the biggest races of the season due to a chain I replaced yesterday due to the cracked plate. I've replaced a rear deraiiler...what's a good alternative to that piece of crap 6700?

Update from my post yesterday. On close examination, there are several cracks in other outer plates on my 6700 chain. My chain has broken twice since purchase on July 1 - today is August 26, 2010. I called the Shimano customer service folks and they admitted they have had a number of failures and to send it in and they will replace it. The person I spoke with attributed it to a problem with a coating process...John

Here is pictures of mine with about 1500 miles. I lube with dumonde tec every 150 miles or so. I never degrease and just wipe the chain after lubing. This method has always worked well for me in the past. I got 4000 miles out of my last 7900 chain before it became stretched. I purchased two chains when I got this one. The other is on my cyclocross bike with about 500 miles. I can't find any cracks in that one yet.

I just returned from LBS which diagnosed failed Ultegra chain on my 3 month old Madone 5.2. Chain did not crack as shown in images here, but side plate bulged, eventually jamming the derailleur, which snapped the hanger and rammed the whole mech up into the spokes. The back wheel locked solid and the mech scored into the chainstay, causing fatal damage to the frame. I was seated and not putting significant power through the drive chain when this happenned. I was lucky not to crash, but was only doing about 10 mph after remounting to look for cause of the skipping chain. The chain came new on the bike and had only about 500 miles on it. I have never had a chain break in 30 years of riding and had looked after this one well as it was on my - now dead - best bike. This is one of several failures seen recently by the LBS guys on Ultegra chains and by reading these posts, it seems only time until someone is seriously injured. A re-call may be required. Nigel